A Russian security agency says Ukrainian intelligence has attempted to steal a Russian strategic bomber by bribing a pilot.

Russia's Federal Security Service, or FSB, said on Monday that the Ukrainian intelligence plotted to steal a Tu-22M3 aircraft, which is capable of carrying nuclear warheads.

It said the Ukrainians recruited a Russian military pilot by offering him money and Italian citizenship, in exchange for his flying and landing the bomber in Ukraine.

The state-run Tass news agency reported the Ukrainians used social media to contact the Russian pilot, specified the target as a bomber capable of carrying nuclear warheads, and offered 3 million dollars as a reward.

The FSB said evidence has been discovered showing that intelligence agencies from NATO countries were involved in the plot.

Meanwhile, Britain's new Defence Secretary John Healey met with Ukrainian President Volodymyr Zelenskyy in the southern Ukrainian city of Odesa on Sunday. Healey said Britain would provide additional support to Ukraine.

His visit to the country took place less than 48 hours after he took office. Healey apparently wanted to show steadfast support for Kyiv even after a change of government in Britain.